package com.miracle9.game.util.encryptionalgorithm;

import java.io.PrintStream;
import java.io.UnsupportedEncodingException;

public class EncryptionAlgorithm
{
  private static char[] ct = {
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 
    'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 
    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 
    'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 
    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 
    'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 
    'w', 'x', 'y', 'z', '0', '1', '2', '3', 
    '4', '5', '6', '7', '8', '9', '+', '/' };
  private static byte[] cu = {
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, 
    -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 
    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, 
    -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 
    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 };
  
  public static String encode(byte[] data)
  {
    StringBuffer sb = new StringBuffer();
    int len = data.length;
    int i = 0;
    while (i < len)
    {
      int b1 = data[(i++)] & 0xFF;
      if (i == len)
      {
        sb.append(ct[(b1 >>> 2)]);
        sb.append(ct[((b1 & 0x3) << 4)]);
        sb.append("==");
        break;
      }
      int b2 = data[(i++)] & 0xFF;
      if (i == len)
      {
        sb.append(ct[(b1 >>> 2)]);
        sb.append(ct[((b1 & 0x3) << 4 | (b2 & 0xF0) >>> 4)]);
        sb.append(ct[((b2 & 0xF) << 2)]);
        sb.append("=");
        break;
      }
      int b3 = data[(i++)] & 0xFF;
      sb.append(ct[(b1 >>> 2)]);
      sb.append(ct[((b1 & 0x3) << 4 | (b2 & 0xF0) >>> 4)]);
      sb.append(ct[((b2 & 0xF) << 2 | (b3 & 0xC0) >>> 6)]);
      sb.append(ct[(b3 & 0x3F)]);
    }
    return sb.toString();
  }
  
  public static byte[] decode(String str)
  {
    try
    {
      return lllIllllIIlIIlll(str);
    }
    catch (UnsupportedEncodingException e)
    {
      e.printStackTrace();
    }
    return new byte[0];
  }
  
  private static byte[] lllIllllIIlIIlll(String str)
    throws UnsupportedEncodingException
  {
    StringBuffer sb = new StringBuffer();
    byte[] data = null;
    data = str.getBytes("US-ASCII");
    int len = data.length;
    int i = 0;
    while (i < len)
    {
      int b1;
      do
      {
        b1 = cu[data[(i++)]];
      } while ((i < len) && (b1 == -1));
      if (b1 == -1) {
        break;
      }
      int b2;
      do
      {
        b2 = cu[
          data[(i++)]];
      } while ((i < len) && (b2 == -1));
      if (b2 == -1) {
        break;
      }
      sb.append((char)(b1 << 2 | (b2 & 0x30) >>> 4));
      int b3;
      do
      {
        b3 = data[(i++)];
        if (b3 == 61) {
          return sb.toString().getBytes("iso8859-1");
        }
        b3 = cu[b3];
      } while ((i < len) && (b3 == -1));
      if (b3 == -1) {
        break;
      }
      sb.append((char)((b2 & 0xF) << 4 | (b3 & 0x3C) >>> 2));
      int b4;
      do
      {
        b4 = data[(i++)];
        if (b4 == 61) {
          return sb.toString().getBytes("iso8859-1");
        }
        b4 = cu[b4];
      } while ((i < len) && (b4 == -1));
      if (b4 == -1) {
        break;
      }
      sb.append((char)((b3 & 0x3) << 6 | b4));
    }
    return sb.toString().getBytes("iso8859-1");
  }
  
  public static void main(String[] args)
    throws UnsupportedEncodingException
  {
    String s = "abcd";
    System.out.println("加密前：" + s);
    String x = encode(s.getBytes());
    System.out.println("加密后：" + x);
    String x1 = new String(decode(x));
    System.out.println("解密后：" + x1);
  }
}
